Cookbook/Lists and strings

Revision as of 10:16, 23 April 2009 by Lenny222 (Talk | contribs)

1 Strings

Since strings are lists of characters, you can use any available list function.

Problem	Solution	Examples
combining two strings	(++)	"foo" ++ "bar" --> "foobar"
combining many strings	concat	concat ["foo", "bar", "baz"] --> "foobarbaz"

Problem	Solution	Examples
accessing the first character	head	head "foo bar baz" --> 'f'
accessing the last character	last	last "foo bar baz" --> 'z'
accessing the character at a given index	(!!)	"foo bar baz" !! 4 --> 'b'
accessing the first `n` characters	take	take 3 "foo bar baz" --> "foo"
accessing the last `n` characters	TODO	TODO
accessing the `n` characters starting from index `m`	drop, take	take 4 $ drop 2 "foo bar baz" --> "o ba"

Problem	Solution	Examples
splitting a string into a list of words	words	words "foo bar\t baz\n" --> ["foo","bar","baz"]
splitting a string into two parts	splitAt	splitAt 3 "foo bar baz" --> ("foo"," bar baz")

"foo\
\bar"               --> "foobar"

Problem	Solution	Examples
converting a character to a numeric value	ord	import Char ord 'A' --> 65
converting a numeric value to a character	chr	import Char chr 99 --> 'c'

Problem	Solution	Examples
reversing a string by characters	reverse	reverse "foo bar baz" --> "zab rab oof"
reversing a string by words	words, reverse, unwords	unwords $ reverse $ words "foo bar baz" --> "baz bar foo"
reversing a string by characters by words	words, reverse, map, unwords	unwords $ map reverse $ words "foo bar baz" --> "oof rab zab"

Problem	Solution	Examples
converting a character to upper-case	toUpper	import Char toUpper 'a' --> "A"
converting a string to upper-case	toUpper, map	import Char map toUpper "Foo Bar" --> "FOO BAR"
converting a character to lower-case	toLower	import Char toLower 'A' --> "a"
converting a string to lower-case	toLower, map	import Char map toLower "Foo Bar" --> "foo bar"

TODO

For high performance requirements (where you would typically consider C), consider using Data.ByteString.

TODO